The invention provides a hydraulic circuit for feeding an actuator (1) comprising first and second chambers (5, 6), the circuit comprising a slide valve (10) with a slide (16) that is movable between first and second extreme positions (18, 19) on either side of a stable central position (17) so that: in the central position, it connects the chambers (5, 6) of the actuator to a return port; in the first extreme position (18), it connects the first chamber (5) to a feed port and the second chamber to the return port; and in the second extreme position (19), it connects at least the second chamber (6) to the feed port. According to the invention, the hydraulic circuit includes pressure-maintaining means (20) for maintaining pressure in the first chamber of the actuator while the slide is passing through the central position on being moved from the first extreme position to the second extreme position.

In an exemplary method of monitoring performance of a fluid driven actuator for a valve, pressurized fluid is supplied through an actuator supply line to an inlet port of the actuator during a first time period to operate the actuator from a normal position to an actuated position. Pressure changes corresponding to a fluid flow condition in the actuator supply line are measured during the first time period, with the measured pressure changes defining a valve cycle pressure profile including a first inflection point corresponding to movement of the actuator from the normal position to the actuated position. The valve cycle pressure profile is analyzed to identify a non-compliant condition in at least one of the valve and the actuator. An output communicating the identified non-compliant condition is then generated.

In an exemplary method of monitoring performance of a fluid driven actuator for a valve, pressurized fluid is supplied through an actuator supply line to an inlet port of the actuator during a first time period to operate the actuator from a normal position to an actuated position. Pressure changes corresponding to a fluid flow condition in the actuator supply line are measured during the first time period, with the measured pressure changes defining a valve cycle pressure profile including a first inflection point corresponding to movement of the actuator from the normal position to the actuated position. The valve cycle pressure profile is analyzed to identify a non-compliant condition in at least one of the valve and the actuator. An output communicating the identified non-compliant condition is then generated.

The invention relates to a press for extruding metal material. The press comprises a hydraulic oil circuit for controlling one or more extrusion pistons movable within corresponding cylinders. Such a circuit comprises a fixed displacement, circulation pump operated by an electric motor with variable rotation speed. The hydraulic circuit comprises a main line and a branch line, along which a shutoff element is arranged. The hydraulic circuit comprises a hydraulic control unit comprising a pilot valve arranged along a pilot line provided with a first segment communicating with the main line and a second discharging segment. Said hydraulic unit is provided to move the shutoff element between an opening position and a closing position of the branch line according to the difference between the oil pressure upstream of the shutoff element and that in the first segment of said pilot line. The hydraulic circuit further comprises a control element which, in an activation condition, and as a result of the activation of said pilot valve, determines a gradual increase of the pressure in the first segment of said pilot line and a corresponding gradual closing movement of said shutoff element causing a consequent gradual increase of the thrust on the piston until the reference speed is reached.

A pneumatic control device includes a base seat unit, a cylinder unit and a time-delay unit. The cylinder unit is mounted the base seat unit, and is able to drive rotational movement. The time-delay unit is mounted to the base seat unit, and includes sequentially interconnected delay switch, flow-limiting valve, pressure accumulator and a control valve. The delay switch is operable to move between an action position whereat the cylinder unit drives the rotational movement, and a non-action position. When the delay switch is moved to the non-action position, the cylinder unit keeps driving the rotational movement for a period of time and then stops.

A pneumatic control device includes a base seat unit, a cylinder unit and a time-delay unit. The cylinder unit is mounted the base seat unit, and is able to drive rotational movement. The time-delay unit is mounted to the base seat unit, and includes sequentially interconnected delay switch, flow-limiting valve, pressure accumulator and a control valve. The delay switch is operable to move between an action position whereat the cylinder unit drives the rotational movement, and a non-action position. When the delay switch is moved to the non-action position, the cylinder unit keeps driving the rotational movement for a period of time and then stops.

A time-based power boost control system. A fluid source supplies fluid. A relief device relieves pressure of the fluid supplied by the fluid source when the pressure of the fluid exceeds a relief pressure level. A control device controls the relief device. When a boost mode in which at least a first level of pressure and a second level of pressure, higher than the first level of pressure, are allowed to be selectively used as the relief pressure level is active, a length of a boost-on time in which the second level of pressure is used as the relief pressure level is shorter than a preset maximum boost-on time limit, and a length of a succeeding boost-off time succeeding the boost-on time in which the first level of pressure is used as the relief pressure level is equal to or longer than a preset minimum boost-off time limit.

The invention provides a hydraulic circuit for feeding an actuator (1) comprising first and second chambers (5, 6), the circuit comprising a slide valve (10) with a slide (16) that is movable between first and second extreme positions (18, 19) on either side of a stable central position (17) so that: in the central position, it connects the chambers (5, 6) of the actuator to a return port; in the first extreme position (18), it connects the first chamber (5) to a feed port and the second chamber to the return port; and in the second extreme position (19), it connects at least the second chamber (6) to the feed port.

According to the invention, the hydraulic circuit includes pressure-maintaining means (20) for maintaining pressure in the first chamber of the actuator while the slide is passing through the central position on being moved from the first extreme position to the second extreme position.

An actuator, such as a pressure actuator or a vacuum actuator, has a housing and a plunger that is guided through the housing. A diaphragm is connected to the housing and to the plunger and forms a gas-tight pressure chamber with the housing. A pressure medium connector is provided on the housing and communicates with the pressure chamber to pressurize the pressure chamber. A braking element is provided on the plunger and enables a braking force can be exerted on the plunger.

A hydraulic brake arrangement for a bicycle with a transmitting unit with a brake lever, and a cylinder housing with a cylinder space, and with a piston unit displaceably received in the cylinder space. The brake lever is operatively coupled with the piston unit by means of an actuating mechanism. The cylinder housing comprises a lever-side end and a receiver-side end. On the receiver-side end, a connection port is configured for coupling a conduction device. On the lever-side end, a connecting opening is configured, through which the actuating mechanism extends into the cylinder space to the piston unit. The connecting opening is configured in a supporting wall extending transverse to the longitudinal axis of the cylinder space and non-detachably connected with the cylinder housing. The piston unit is inserted into the cylinder space through the connection port.